Radish Companion Plants
Raphanus sativus · brassica family · rotation group: brassica
The best companion plants for radish are Cabbage, Broccoli, Lettuce, Carrot, and Pea. Avoid planting radish near Cabbage, Hyssop, Turnip. Of the 11 pairings recorded here, 2 are supported by published research and 9 are traditional practice with no controlled evidence behind them.
What to plant with radish
| Plant | Claimed benefit | Evidence | What the evidence actually shows |
|---|---|---|---|
| Broccoli | Radish acts as a sacrificial flea beetle host protecting slower-growing broccoli seedlings. | Research-backed | Supported by extension IPM guidance and on-farm SARE trials; note the radish crop itself is sacrificed and must be destroyed or it becomes a pest reservoir. |
| Cabbage | Radish sown a week or two ahead of cole crops pulls flea beetles onto itself and away from the cash crop. | Research-backed | This is one of the best-evidenced companion tactics in the dataset: multiple replicated trials confirm daikon and radish work as flea beetle trap crops, with efficacy depending on sowing 1-2 weeks early, using roughly 10% of the planting area, and placing the trap as a perimeter. |
| Carrot | Radish marks slow-germinating carrot rows and loosens the soil crust as it emerges. | Traditional | A well-established practical technique with obvious mechanics but no controlled yield data; the claim that radish improves carrot root quality is unsupported. |
| Lettuce | Radishes mature in three to four weeks and are pulled before lettuce needs the space. | Traditional | A genuine intercropping efficiency, not a biological interaction; no trial required or found. |
| Marigold | Marigolds are widely said to repel flea beetles from radish and other brassicas. | Traditional | University of Minnesota Extension states plainly that there is little research to support marigolds or green onions repelling flea beetles, and controlled work on marigold as an insect repellent has repeatedly failed; marigold's real, evidenced benefit is nematode suppression when grown as a dense preceding cover crop. |
| Nasturtium | Nasturtium is said to draw aphids and flea beetles away from radish. | Traditional | Nasturtium's glucosinolate chemistry makes the trap-crop idea plausible and gardeners report strong aphid preference, but the sources are blogs and observation rather than replicated trials. |
| Pea | Peas and radish share the early spring window and the pea row shades radish as weather warms. | Traditional | Shared season is real; the commonly attached claim that pea nitrogen feeds the radish in the same season is not supported by isotope-tracer evidence. |
| Spinach | Radish and spinach share cool-season timing and radish can decoy leafminers and flea beetles. | Traditional | The trap-crop effect is proven for flea beetles in brassicas but has not been tested with spinach as the protected crop. |
What not to plant with radish
| Plant | Claimed problem | Evidence | What the evidence actually shows |
|---|---|---|---|
| Cabbage | As a brassica itself, radish shares clubroot and cabbage root maggot with the cole crops. | Traditional | A genuine tension: radish is simultaneously a useful flea beetle trap crop and a same-family host that can build clubroot inoculum, so it should not be used in a bed where clubroot is known. |
| Hyssop | Hyssop is traditionally listed as inhibiting radish growth. | Traditional | This pairing traces back to early companion-planting books and has no experimental support of any kind. |
| Turnip | Turnips are close relatives that concentrate the same root maggot and clubroot pressure. | Traditional | Standard same-family rotation caution rather than a measured adjacency penalty. |
The honest verdict
Of everything gardeners recommend planting alongside radish, 2 pairings have been tested properly: Cabbage, Broccoli. Those are the ones worth planning your bed around.
The remaining 6 pairings on this page are traditional practice. They circulate on every companion planting chart online, but we could not find controlled evidence testing them. They are not wrong so much as unverified — most cost nothing to try, and interplanting flowers and herbs has its own well-documented benefit of pulling pollinators and predatory insects into the garden.
Every row above links to the publication it came from. See how we grade evidence.
Growing radish: the numbers
| Sun | Full sun (6+ hours) |
|---|---|
| Water | Moderate |
| Spacing | 2 in apart · 12 in between rows · 16 per square foot |
| Mature size | about 8 in tall |
| Soil pH | 6–7 |
| Days to maturity | 21–45 days |
| Frost tolerance | Hardy — takes hard frost |
| Containers | Yes — 2 gallon minimum |
| Typical yield | 1 root |
| Common pests | flea beetles, cabbage root maggot, aphids, wireworms, cutworms |
| Common diseases | clubroot, black rot, Alternaria leaf spot, root rot |
When to plant radish
Zone 6b shownDirect sow outdoors: Mar 20 – Apr 2 — 3 weeks before last frost
Expected harvest: Apr 10 – May 4 — 21–45 days from planting
Fall planting: Sep 15 – Sep 28 — 6 weeks before your first fall frost
Those dates are for zone 6b. Get your own dates by ZIP code →
Varieties worth knowing
seeds- Cherry Belle — round red standard, very fast, roughly 22-25 days
- French Breakfast — oblong red with white tip, mild, 25-29 days
- Easter Egg II — mixed red, purple, pink and white roots, 25-29 days
- Watermelon / Red Meat — large winter type, green skin with pink flesh, 45-49 days
Variety names link to seeds on Amazon. As an Amazon Associate we earn from qualifying purchases. These are the varieties named in the extension sources for this crop, not a paid placement — where a source recommended a variety for a specific reason, that reason is the note beside it.
Put it in a bed
The garden planner checks every square against this ledger as you place crops — if you drop radish next to something recorded as a bad neighbour, the square turns red and tells you why.
Records for the plants named above:
Same rotation group (brassica) — don't follow one with another:
Radish companion planting questions
What should not be planted next to radish?
How far apart should radish be planted?
Does companion planting with radish actually work?
When should I plant radish?
Sources for this record
- Growing radishes in home gardens — University of Minnesota Extension
- How to Grow Radishes in Your Garden — Utah State University Extension
- Carrot, Beet, Radish & Parsnip — Clemson Cooperative Extension HGIC
- Radish — University of Illinois Extension
Record compiled 2026-07. Spot an error or a study we missed? Tell us and we'll correct the entry.